We moved to a new shiny office and my boss asked me if we could do something more ... special instead of the usual wireless bell going "ding-gong".

I came up with the idea of using a Raspberry Pi with a button and a wifi dongle, which when the button get's pushed rings the receptionist's desk phone. Then she can pick up and talk to whoever is at the door, eventually to go open it.

Boss says cool let's do it :)

So I got a Pi, some styroboard and me printer and started on it.

First I needed Linux running on the thing, I messed around trying to use Gentoo to get a kernel + rootfs for a while but it took way too long so I tried archlinuxarm for a while, which worked for initial tests but it's bloated and unoptimized.

In the end I have settled for buildroot which is a great set of scripts and makefiles to creeate a very custom and sleek rootfs + kernel. Even better someone worked on it before : https://github.com/nezticle/RaspberryPi-BuildRoot Good job man ;)

In less then 3 hours compiling on my quad core I had a nice custom Linux to base on, which booted right away.

It runs using less than 32 Mb of RAM, 200Mb of SD (without any clean up), and it's real fast :D

One problem with the Pi is that it has audio output but no input.

To solve that I added an old usb conference speaker in the mix which besides the mic it has it's own amplifier.

The problem was that plugging both the wifi dongle and speaker in the Pi made it reset due to power draw.

To fix that I needed a powered hub ... which I could not get cheap and fast. However I found lots of unpowered ones so I got one of those and just added power :)

Next was the SIP client which should call the VoIP Phone of the reception.

Initially I have written one in Python based on the PJSIP library wrappers ... however I had all sorts of troubles keeping the audio connection up. Now that I think about it, the problem was probably in the settings I used .

Anyways I switched to C after finding some samples coming with the library source, hacked my own little app together and had the Pi calling a Phone :D

Software working I needed a way to power the thing, I looked into some batteries, did some math and came to the conclusion (thanks Antonio and others in shoutbox) that even using a 90aH car battery it would still not be enough to keep the thing running trough a week :/

It was pretty clear I would need a cable trough the wall in the door way. For a while things stalled as the building managers did not allow us to drill holes, but in the end we managed :)

Once this was done, the only thing remaining was a case for the thing and I thought that buying one would do no justice so I made it using my cool tool BumbleBee.

I used Styrofoam board for the panels and printed the corners, the button, and the speaker + microphone cover. And what came out is in the pictures.